Crouchback and bishop Nikolas of Oslo, and the war continued uninterrupted. The Bagler were strongest in the Oslofjord-area, while Trøndelag was a stronghold of the Birkebeiner, but battles and ambushes took place throughout the country. In the end the bishops were able to negotiate a settlement between the two sides, confirmed at a meeting at Kvitsøy in 1208. The Bagler king Philippus was to remain in control of eastern Norway but renounce the title of king, leaving the Birkebeiner King Inge nominally sole ruler of the country. In the event, Philippus continued to style himself king until his death, but peace between the Bagler and Birkebeiner was preserved until 1217. Reconciliation between Bagler and Birkebeiner In 1217 King Inge Bårdsson died. The Birkebeiner, nervous at being left without a leader in case of a Bagler attack, chose the 13-year-old Håkon Håkonsson as their new king, while the jarl Skule Bårdsson was made leader of the army. Håkon Håkonsson was a posthumously-born son of Håkon Sverresson, of whom the Birkebeiner had not been aware when electing Inge their king in 1204—he had arrived at King Inge's court in 1206. Skule was the brother of King Inge and had designs on the throne for himself; however, he contented himself for the time being with leadership of the army, which made him, de facto, the most powerful man of the kingdom. When the Bagler king Philippus died later the same year, Skule moved quickly. He managed to persuade the Bagler not to elect a new king of their own. Instead, they officially dissolved their party and swore fealty to Håkon Håkonsson, thus reuniting the kingdom. Discontented elements remained and a revolt in eastern Norway, led by a son of Erling Stonewall called Sigurd Ribbung, dragged on until 1227. After Sigurd died a natural death the rest of his party gave up their revolt. The year 1227 is sometimes considered the end of the civil war era, but most often the term is extended to include the revolt of Skule Bårdsson in 1239–40. The election of Håkon as king in 1217 seems to have been considered something of a temporary solution until a permanent arrangement could be reached, and Skule undoubtedly hoped that he would soon take over the throne. At a gathering of the most important men of the kingdom in Bergen in 1223, Skule launched his candidacy to the throne of Norway